Geometric Morphometric Versus Genomic Patterns in a Large Polyploid Plant Species Complex

Abstract

Plant species complexes represent a particularly interesting example of taxonomically complex groups (TCGs), linking hybridization, apomixis, and polyploidy with complex morphological patterns. In such TCGs, mosaic-like character combinations and conflicts of morphological data with molecular phylogenies present a major problem for species classification. Here, we used the large polyploid apomictic European Ranunculus auricomus complex to study relationships among five diploid sexual progenitor species and 75 polyploid apomictic derivate taxa, based on geometric morphometrics using 11,690 landmarked objects (basal and stem leaves, receptacles), genomic data (97,312 RAD-Seq loci, 48 phased target enrichment genes, 71 plastid regions) from 220 populations. We showed that (1) observed genomic clusters correspond to morphological groupings based on basal leaves and concatenated traits, and morphological groups were best resolved with RAD-Seq data; (2) described apomictic taxa usually overlap within trait morphospace except for those taxa at the space edges; (3) apomictic phenotypes are highly influenced by parental subgenome composition and to a lesser extent by climatic factors; and (4) allopolyploid apomictic taxa, compared to their sexual progenitor, resemble a mosaic of ecological and morphological intermediate to transgressive biotypes. The joint evaluation of phylogenomic, phenotypic, reproductive, and ecological data supports a revision of purely descriptive, subjective traditional morphological classifications.

Apomixis goes a long way: Genetic evidence of persistence and long‐distance seed dispersal in an ancient landscape

“…The ability of this species to persist in different niches during unfavourable times may be the result of its allopolyploid status, as allopolyploidy could indirectly help to establish highly heterozygous apomictic individuals in a novel ecological niche by increasing adaptive potential (Hodač et al, 2023;. Our findings support the notion that biotic responses to changing climatic conditions in old unglaciated landscapes may be largely idiosyncratic and species specific (e.g.…”

“…glutinosa has persisted across these various habitats during periods of climatic change rather than contracting to refugial areas during the repeated cycles of aridification that characterised the Plio/Pleistocene mid latitude continental regions, where the ranges have provided some refugial buffer for other taxa (Byrne et al., 2017; Pepper et al., 2011). The ability of this species to persist in different niches during unfavourable times may be the result of its allopolyploid status, as allopolyploidy could indirectly help to establish highly heterozygous apomictic individuals in a novel ecological niche by increasing adaptive potential (Hodač et al., 2023; Hojsgaard & Hörandl, 2019). Our findings support the notion that biotic responses to changing climatic conditions in old unglaciated landscapes may be largely idiosyncratic and species specific (e.g.…”

Phylogenomics of Southern European Taxa in the Ranunculus auricomus Species Complex: The Apple Doesn’t Fall Far from the Tree

“…For example, R. pindicola is remarkably isolated compared to the rest of the taxa examined here and may therefore represent a divergent, earlier branching lineage [50]. Morphologically, R. pindicola resembles R. notabilis in having the same type of leaf cycle, but with less divided and more pedate spring leaves and glabrous receptacles, suggesting a mosaic-like character combination as typical for apomictic hybrids rather than for an autopolyploid [50,54]. The population is tetraploid and has very low pollen quality as typical for apomicts [50].…”

Converging forms: an examination of sub-Arctic, circumarctic, and Central Asian Ranunculus auricomus agg. populations

“…Examination of the individual representatives of the R. monophyllus group across Eurasia revealed significant differentiation but no clear grouping of the samples of this taxon. This mirrored previous investigations into other taxa within R. auricomus agg., whereby habit did not correspond to genetic relatedness (Karbstein Bradican et al, 2023;Hodačet al, 2023). This is likely due to facilitating significant phenotypic plasticity in the group, perhaps further facilitated by the history of hybridization and concurrent polyploidy (Hodačet al, 2023).…”